mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-05 16:37:50 +00:00
No description
351a0a3fbc
ioctl EXT4_IOC_CHECKPOINT checkpoints and flushes the journal. This includes forcing all the transactions to the log, checkpointing the transactions, and flushing the log to disk. This ioctl takes u32 "flags" as an argument. Three flags are supported. EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN can be used to verify input to the ioctl. It returns error if there is any invalid input, otherwise it returns success without performing any checkpointing. The other two flags, EXT4_IOC_CHECKPOINT_FLAG_DISCARD and EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT, can be used to issue requests to discard or zeroout the journal logs blocks, respectively. At this point, EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT is primarily added to enable testing of this codepath on devices that don't support discard. EXT4_IOC_CHECKPOINT_FLAG_DISCARD and EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT cannot both be set. Systems that wish to achieve content deletion SLO can set up a daemon that calls this ioctl at a regular interval such that it matches with the SLO requirement. Thus, with this patch, the ext4_dir_entry2 wipeout patch[1], and the Ext4 "-o discard" mount option set, Ext4 can now guarantee that all file contents, file metatdata, and filenames will not be accessible through the filesystem and will have had discard or zeroout requests issued for corresponding device blocks. The __jbd2_journal_erase function could also be used to discard or zero-fill the journal during journal load after recovery. This would provide a potential solution to a journal replay bug reported earlier this year[2]. After a successful journal recovery, e2fsck can call this ioctl to discard the journal as well. [1] https://lore.kernel.org/linux-ext4/YIHknqxngB1sUdie@mit.edu/ [2] https://lore.kernel.org/linux-ext4/YDZoaacIYStFQT8g@mit.edu/ Link: https://lore.kernel.org/r/20210518151327.130198-2-leah.rumancik@gmail.com Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.